1. Field of the Invention
The present invention relates to an inhibitory agent suitable for kneaded meat, especially frozen fish surimi; a drip-inhibitory agent; an inhibitory agent for spongy-meat-formation induced by freezing; an agent for enhancing the stability formation of fish surimi; kneaded meat and process thereof; food products, including kneaded meat of poultry and animals, free of phosphate and with suppressed freezing-denaturation; a method for freezer storage for kneaded meat; a process for producing fish and meat paste products, especially, kamabokos, fish sausages, and kneaded meat of poultry and animals; a method for enhancing the formation of stability of kneaded meat; and a method for increasing the yield of kneaded meat.
2. Description of the Prior Art
In the field of recent food industry, it may tend to reduce or even avoid the use of food additives. Consumers"" minds or feelings and social environment make food processors to explore food products, which are suitable for such commercial needs, and to reduce food additives as much as possible. Particularly, phosphates such as sodium pyrophosphate and sodium polyphosphate are used in fish and meat paste products to improve their freezing tolerance and moisture-retaining ability. However, excessive amount of intake of them may result in an unsatisfactory inhibition of absorbing calcium and minerals by the body, and may susceptibly induce diseases such as osteoporosis, growth inhibition, and taste-blindness. Because of this, the above tendency to avoid or even stop the use of phosphates is on going, particularly, movement or campaign to eliminate phosphates from fish paste products has been strikingly highlighted.
There exists a quite hard problem to be overcome in producing fish meat products without using phosphates while keeping the satisfactory processibility. Conventional frozen-surimi (frozen minced fish meat) free of phosphate, can be processed with only sugar, i.e., sucrose, in an amount of 5% by weight to frozen surimi available at stores and of 8% by weight to those which are processed and stored on ships. In these products, sugar only exerts a relatively-lesser inhibitory activity for freezing-induced protein-denaturation, and fails to keep their high-quality for a relatively-long period of time. Therefore, raw surimi should be used in some fields even though it is partial. In other words, raw surimi should be used without intention even if it is more quickly deteriorated than frozen surimi, meaning that it could not be diluted or brought up volume with water, it has no economical benefit and has only 3- to 4-days of shelf-life even under cold-storage conditions.
In conventional frozen-surimi in general, the protein denaturation thereof has been tried to be inhibited using 5% by weight of sucrose and 0.2% by weight of phosphate(s). Fish meat proteins are susceptible to denaturation when frozen and to lose their solubility against salts. The mechanism of the denaturation has not yet been solved, but the main causative is deemed to be the influence of calcium and magnesium on proteins, resulting in a use of phosphates which inhibit the denaturation of proteins.
It is understood that sugar fines down ice crystals, which are formed by freezing water in myofibrils of fish meat, and prevents the dehydration of proteins. Fish meat myosins in rod-shape molecules associate each other by forming intermolecular cross-links during cold storage, and coagulate by forming floc when the rod-shape molecules proceed to associate. Freezing denaturation is deemed to be triggered by the change of state of water. Proteins and other components in living tissues generally exist in a state where they are sufficiently saturated with water in such a manner that the molecular surfaces are covered with water. As a result, the higher-order structure of proteins is stabilized. It is understood that intramolecular bonds of hydrogen- and hydrophobic-bonds in proteins inevitably correlate to hydration state. Freezing of food products causes the icing and transfer of water, resulting in a removal of water around protein molecules and of hydration water partially or substantially wholly, and leading to an estimation of that the molecules are highly-dehydrated by some degree to loosen and cut the intermolecular cross-links and to confuse the higher-order structure of proteins. Thus, the effect of sugar is considered as follows: It physically causes ice-point reduction, fines down ice crystals, and prevents protein damage.
Stabilization of the quality of surimi free of phosphate, i.e., the prevention or inhibition of protein denaturation during cooling and freezing is quite impossible with only sugar because proteins are susceptible to denaturation during freezer storage, and then gelatinized and sponged to lose moisture-retaining ability by a large margin.
Under these circumstances, Japanese Patent Kokoku No. 23,385/72 discloses a conventional inhibitory agent for protein denaturation and a process for producing frozen-surimi; a technique for inhibiting the freezing,denaturation of surimi by adjusting the pH of surimi before freezing to pHs of 7.5 to 9, and freezing the resulting surimi. Japanese Patent Kokai Nos. 135,927/95 and 9,931/96 disclose another techniques for inhibiting the freezing denaturation of fish surimi by adding trehalose.
Suisan-Kako-Shin-Genryo-Kalhatsu-Jigyo-Hokokusho (Annual Report of 1997 by the Project of Development for New Fishery Processing Materials) in 1997, published on July in 1998 by the Fishery Processing Division of Fishery Administration Department of Fishery Agency of Japan discloses a technique comprising mincing xe2x80x9ctokage-esoxe2x80x9d, i.e., Saurida elongate, and Atlantic cutlassfish, leaching the mixture in an alkaline electrolytic water with a pH of 10 to 11, dehydrating the mixture, adding sucrose and trehalose to the dehydrated mixture, and freezing the resulting mixture into a frozen surimi with improved gel-forming ability.
In conventional techniques using either trehalose or alkaline electrolytic water for leaching fish meat, there found insufficient inhibitory effect on freezing denaturation; the product yield reduction by dripping, spongy meat formation by freezing, and formation reduction of setting of fish surimi. Thus, development of higher technology will be highly appreciated.
In the prior art disclosed in the above Suisan-Kako-Shin-Genryo-Kaihatsu-Jigyo-Hokokusho (Annual Report of 1997 by the Project of Development for New Fishery Processing Materials), alkaline leaching reduces the product yield, and electrolytic water used for the leaching results in a problem of wastewater treatment. In general, kamaboko prepared with surimi containing a residual alkali may be incorporated into products, resulting in fragile mouth feel; Alkali-removing step should be required after alkaline leaching to avoid leached surimi from becoming to show alkaline pHs carefully.
The present invention was made based on the above conventional drawbacks, and the objects according to the present invention are to provide: An inhibitory agent for protein denaturation with a relatively-high suppressed freezing-denaturation inhibitory effect, a drip-inhibitory agent, an inhibitory agent for forming sponge-texture when freezed, an enhancer for forming setting of kneaded fish surimi, kneaded meat with suppressed freezing denaturation and process thereof, a food product including kneaded meat of poultry and animals free of phosphate and with suppressed freezing-denaturation, a method for freezer storage for kneaded meat, a process for producing kneaded meat, particularly, fish and meat paste products; kamabokos, sausages of fish meat, and kneaded meat of poultry and animals, a method for enhancing the formation of setting of the products, and a method for increasing the yield of these products.
To attain the above objects, the present inhibitory agents for protein denaturation, dripping, and formation of sponge texture by freezing, as well as the present agent for enhancing the formation of setting of fish surimi are characterized in that they comprise sorbitol and/or trehalose, or another saccharides along with sorbitol and/or trehalose; and a pH-controlling agent capable of adjusting the pH of kneaded meat to alkaline pHs. The pH-controlling agent used in the present invention includes those which can increase the pH of kneaded meat to an alkaline pH higher than the initial pH, even if the pH of the kneaded meat after pH adjustment is an acid pH. Preferably, alkaline pHs exceeding 7 but below 10, and more preferably those exceeding 7.5 but below 9.5. In particular, in the present inhibitory agents for protein denaturation, dripping, and formation of sponge texture by freezing, and the agent for enhancing the formation of setting of fish surimi, sodium carbonate and/or potassium carbonate can be preferably used as the present pH-controlling agent where the carbonates can be preferably used in an amount of from 0.05% by weight to 10-times by weight of the total amount of sorbitol, trehalose, and another saccharides, and most preferably in an amount in the range of 1-5% by weight.
The inhibitory agents for protein denaturation, dripping, and formation of sponge texture by freezing, and the agent for enhancing the formation of setting of fish surimi according to the present invention preferably further contain an emulsifier such as sucrose fatty acid esters. The emulsifier should preferably be incorporated into the present agents in an amount of from 10% by weight to 10-times by weight of the amount of the pH-controlling agent, and most preferably in an amount of from the equal amount to 2-times amount of the pH-controlling agent. The emulsifier exerts an inhibitory effect on freezing denaturation by inhibiting the formation of ice crystals. The agents according to the present invention should preferably contain sweeteners with glycoside sweeteners. The sweeteners used in the present invention are, for example, sodium glycyrrhizinate, licorice extract, and stevioside sweetener, which are mainly used to mask salty taste of the pH-controlling agent and to sweeten and stabilize the emulsifier. The drip inhibitory agent can be used as one for improving the product yield.
The present kneaded meat with suppressed freezing-denaturation comprises the present inhibitory agent for protein denaturation, and further has a characteristic feature of an alkaline pH exceeding 7 but below 10. The present kneaded meat should preferably contain 1-20% by weight of trehalose and 0.01-10% by weight of sodium carbonate and/or potassium carbonate, and has a pH exceeding 7.5 but below 9.5. The present food products free of phosphate and with suppressed freezing-denaturation comprise, as a characteristic feature, the present inhibitory agent for protein denaturation and have an alkaline pH exceeding 7 but below 10, and preferably a pH exceeding 7.5 but below 9.5.
The present process for producing kneaded meat with suppressed freezing-denaturation is characteristic of incorporating into a kneaded meat (i) sorbitol, trehalose, or another saccharide(s) along with sorbitol and/or trehalose; and (ii) a pH-controlling agent to adjust the pH of kneaded meat to an alkaline pH exceeding 7 but below 10; In particular, it is preferable to incorporate into a kneaded meat 1-20% by weight of trehalose and 0.01-10% by weight of sodium carbonate and/or potassium carbonate, and to adjust the pH of the kneaded meat to a pH exceeding 7.5 but below 9.5. For example, such a kneaded meat is made of fish surimi. Fish surimi and another kneaded food products can be admixed with other additives includes amylaceous substances such as corn starch, sweet potato starch, potato starch, wheat starch, and barley starch; seasonings such as sodium glutamate and salt; preservatives such as sorbic acid; emulsifiers such as sucrose fatty acid ester; glycoside sweeteners such as sodium glycyrrhizinate, licorice extract, and stevioside sweetener; and optionally one or more additives of colors and flavors. The emulsifiers can be preferably incorporated into kneaded meat in an amount of 0.01 to 1% by weight, and preferably 0.1 to 0.2% by weight of the kneaded meat.
The present method for freezer storage of kneaded is featured in that it comprises: (a) incorporating into a kneaded meat sorbitol, trehalose, or another saccharide(s) containing sorbitol and/or trehalose; (b) incorporating into the mixture a pH-controlling agent to adjust the pH of the mixture to an alkaline pH exceeding 7 but below 10, and preferably a pH exceeding 7.5 but below 9.5; and subjecting the resulting mixture to freezer storage.
The present process for producing fish and meat paste products, particularly, kamaboko and fish sausage is characterized in that it is processed with the following fish surimi as a material obtained by: incorporating into a fish surimi 1-20% by weight of trehalose and 0.01-10% by weight of sodium carbonate and/or potassium carbonate to adjust the pH of the resulting surimi to an alkaline pH exceeding 7 but below 10, and preferably a pH exceeding 7.5 but below 9.5.
The present process for producing kneaded meat processed with poultry and animals can be prepared using kneaded meat of poultry and animals obtained by incorporating thereunto 1-20% by weight of trehalose and 0.01-10% by weight of sodium carbonate and/or potassium carbonate, and adjusting the resulting mixture to pHs exceeding 6 but below 10, preferably pHs exceeding 7 but below 10, and more preferably pHs exceeding 7.5 but below 9.5.
The present methods for enhancing the formation of setting and for increasing the product yield are characteristic of using 1-20% by weight of sorbitol, trehalose, another saccharides, or mixtures thereof with respect to the weight of surimi, and an adequate amount of a pH-controlling agent; and adjusting the resulting mixtures to alkaline pHs exceeding 7 but below 10, and preferably pHs exceeding 7.5 but below 9.5.